Initially, I thought this was some sort of deer fly...from its gestalt (especially that "beak") and behavior (flew inside the car, then buzzed loudly at the window, etc.). Indeed, it turns out it is a biter (or more accurately, a "slash & lapper")...but the eyes and antenna didn't look right for a deer fly.

My hesitations were validated when it keyed unambiguously to family Rhagionidae, genus Symphoromyia in MND(1), Cole(2), and Curran(3). This is a female, from the well-separated eyes and conspicuously large blood-feeding mouthparts. (Males are holoptic(4) and do not feed on blood.) Some salient characters for the ID's to family and genus: empodia pulvilliform (see right foreleg); 1st antennomere (or 3rd segment...after scape and pedicel) concave below the dorsally attached arista (see 2nd photo in series); clypeus conspicuous, convex; anal lobe and alula well-developed; hind tibia with 1 terminal spur (note that it looks like there are two tibial spurs visible through the (R5 cell of the) right wing in the photo above, but that's because the fly was rubbing its two hind-legs together! :-)

Using the key for females on pg. 118 of Aldrich's 1915 "The dipterous genus Symphoromyia in North America" (PDF here), this specimen keys almost immediately to species S. sackeni as follows:

1a. Third joint of antenna concave at apex, below the arista....2
1b. Third joint convex as usual...................................5
2a. Abdomen yellow in ground color( Washington; California)...sackeni, new species
2b. Abdomen black..............3 (key continues from here...)

The description of the female of S. sackeni on pg 140 of Aldrich (1915) fits my specimen very well, and it occurs in CA. Aldrich's key treated females for 17 of the 22 species he covered. Fifty-four years later, Cole(2) discussed the genus and indicated no new taxa up to then (though one species was synonymized, and others described for sexes missing in Aldrich's work). Regarding S. sackeni, Cole wrote: "abdomen wholly yellow in the female, yellow on the sides in the slender, dark male, the species being unique in this coloration". This statement seems to strongly reinforce a putative ID of S. sackeni here. However, the "uniqueness" Cole had in mind may have referred to both the female and male colorations, taken together...in which case the reinforcement is weaker.

If the taxonomy in the genus Symphoromyia had stayed static since 1969, I may have made a guide page for S. sackeni and placed these images there. But as might be expected, more species have been described since then. The excellent 2004 worldwide revision of rhagionid genera by Kerr(4) lists 30 species with types in the USA (29 of which appear on the ITIS Symphoromyia page). The species S. sackeni is on this list, so it hasn't been buried in synonymy. But with the addition of 9 more species, the wholly yellow female that Cole saw fit to remark on may no longer be unique...and this could now be something else.

Any comments, corrections, or confirmations here would be much appreciated.